Forecast and Analysis

Regional Migration Analysis: 11 – 18 April 2013

Andrew Farnsworth The Cornell Lab Apr 19, 2013

Continental Summary:

Light to moderate movements occurred across the West, particularly early in the forecast period in California and the Desert Southwest, while a complex stalled front brought light to moderate and even locally heavy movements to many different areas of the East. Species on the move this week included numerous shorebirds, Ruby-crowned Kinglet, numerous warblers, Indigo and Painted Buntings, and numerous sparrows including Chipping, Savannah, and White-throated Sparrows.



Light to moderate movements began the forecast period across southern portions of the region, as scattered precipitation shut down most movements in northern areas. By Monday night into midweek, more widely scattered light movements occurred across the region where conditions were marginal or favorable and without precipitation. The end of the forecast period saw continued light to moderate movements over California and widely scattered light movements across the remainder of the region, particularly the Desert Southwest and some portions of the northern Rockies, while precipitation shut down movements in parts of the Pacific Northwest. Species on the move this week included Marbled Godwit, Vaux’s Swift, Say’s Phoebe, Hermit Thrush, Yellow-rumped and Orange-crowned Warblers, and McCown’s Longspur.

Great Plains

High pressure over the region made for a generally slow week, with an exception late last weekend, when light to moderate movements occurred locally along a frontal boundary over Nebraska and Kansas. For the most part, the combination of precipitation interspersed with cool and marginal to unfavorable conditions inhibited most nocturnal movements through the forecast period. Species on the move this week included many shorebirds like Upland Sandpiper, Long-billed Curlew, Hudsonian Godwit, Wilson’s Phalarope, Chimney Swift, and Eastern Kingbird.

Upper Midwest and Northeast

After a slow start to the weekend, departing high pressure over New England and approaching low pressure over the western Great Lakes brought light to moderate movements to many areas of the region by Sunday night. As the frontal boundary organized and moved East, light to moderate movements spread into New England and continued over the Mississippi and Ohio River valleys. By Tuesday night the frontal boundary pushed across much of New England but stalled farther south and west, bring concentrations and mini-fallouts along the frontal boundary where rain fell from southeastern New York through the Virginia Appalachians. By Wednesday night light movements occurred North and East of the stationary front from the Ohio River valley to DelMarVa, whereas more moderate movements occurred to the South of this boundary. The end of the period saw this front develop into a more organized cold front, with primarily light movements in marginal conditions occurring from the Ohio River valley East to the Atlantic and North into New England. Species on the move this week included Barn Swallow, House Wren, Ruby-crowned Kinglet, Palm, Pine, Yellow-rumped, and Black-and-white Warblers, White-throated, Chipping and Savannah Sparrows, and Dark-eyed Junco.

Gulf Coast and Southeast

A front bisecting the region slowed or stopped much western trans-Gulf movement while spawning moderate flights farther East to begin the period. The passage of the front was followed by several days of light to moderate movements in many areas, building to include some locally heavy movements through the middle of the week in Texas, Georgia, and northern Florida. More widespread light to moderate movements occurred on Wednesday night, from Texas through the Florida Keys and north to Tennessee and the Carolinas. The period ended with a bang along the Texas and Louisiana coasts as a trans-Gulf migrants encountered a strong front at the coast, creating numerous fallouts, and with light to moderate and locally heavy movements in the remainder of the Southeast to the east of the front. Species on the move this week included Chuck-will’s-widow, Swainson’s Thrush, Yellow, Blackpoll, Black-throated Blue, Black-throated Green, Blue-winged, and Kentucky Warblers, Northern Waterthrush, Painted and Indigo Buntings, and Dickcissel.